Eversible branch stent-graft and deployment method

ABSTRACT

A method of deploying an eversible branch stent-graft includes deploying the eversible branch stent-graft into a main vessel such that a collateral opening in a main stent-graft of the eversible branch stent-graft is aligned with an ostium of a branch vessel emanating from the main vessel. A branch stent ring suture threaded though outer exposed crowns of an outer stent ring of the branch stent-graft is grasped and pulled through the collateral opening to evert the branch stent-graft into the branch vessel as a branch anchor suture is removed to release a protruding end of a branch stent-graft from a proximal end of the main stent-graft.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an intra-vascular device and method. More particularly, the present invention relates to a device for treatment of intra-vascular diseases.

2. Description of the Related Art

A conventional main (vessel) stent-graft typically includes a radially expandable reinforcement structure, formed from a plurality of annular stent rings, and a cylindrically shaped layer of graft material, sometimes called graft cloth, defining a lumen to which the stent rings are coupled. Main stent-grafts are well known for use in tubular shaped human vessels.

To illustrate, endovascular aneurysmal exclusion is a method of using a main stent-graft to exclude pressurized fluid flow from the interior of an aneurysm, thereby reducing the risk of rupture of the aneurysm and the associated invasive surgical intervention.

Main stent-grafts with custom side openings are sometimes fabricated to accommodate the particular vessel structure of each individual patient. Specifically, as the location of branch vessels emanating from a main vessel, e.g., having the aneurysm, varies from patient to patient, main stent-grafts are fabricated with side openings customized to match the position of the branch vessels of the particular patient. Branch stent-grafts are then deployed within the side openings to perfuse the branch vessels. However, deployment of branch stent-grafts has proven to be complicated and time-consuming thus increasing the risk of the procedure.

To avoid custom fabrication of main stent-grafts, side openings in the main stent-graft may be formed in situ. Illustratively, the main stent-graft is placed in the main vessel, e.g., the aorta, to exclude an aneurysm. Side openings are made in situ to correspond to and perfuse the branch vessels.

However, deployment of the main stent-graft temporarily interrupts perfusion to the branch vessels until the side openings are formed in the main stent-graft. To illustrate, perfusion to the brain via the carotids cannot be interrupted for any significant interval of time. Accordingly, the formation of side openings in a main stent-graft in situ is a complicated and risky procedure.

SUMMARY OF THE INVENTION

In accordance with one example, a method of deploying an eversible branch stent-graft includes deploying the eversible branch stent-graft into a main vessel such that a collateral opening in a main stent-graft of the eversible branch stent-graft is aligned with an ostium of a branch vessel emanating from the main vessel. A branch anchor suture is removed to release a protruding end of a branch stent-graft from a proximal end of the main stent-graft. A branch stent ring suture threaded through the outer exposed crowns of an outer stent ring of the branch stent-graft is grasped and pulled through the collateral opening to evert the branch stent-graft into the branch vessel.

As set forth above, the protruding end of the branch stent-graft is initially located at the proximal end of the main stent-graft. Further, the collateral opening is aligned with the ostium of the branch vessel. Accordingly, a portion of the blood flow through the main vessel enters the branch stent-graft at the protruding end, travels through a branch lumen of the branch stent-graft, exits through the collateral opening and passes into the branch vessel.

In this manner, the branch vessel is perfused through the branch stent-graft during the entire procedure of deploying the everted branch stent-graft. Accordingly, perfusion to the brain via the carotids is not interrupted for any significant interval of time reducing the complexity and risk of the procedure. Further, deployment of the branch stent-graft into the branch vessel is simple and direct.

Embodiments are best understood by reference to the following detailed description when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an eversible branch stent-graft in a deployed configuration in accordance with one embodiment;

FIG. 2 is a schematic cross-sectional view of the eversible branch stent-graft of FIG. 1 being deployed in a main vessel in accordance with one example;

FIG. 3 is an enlarged schematic cross-sectional view, partially cutaway, of a region III of the eversible branch stent-graft of FIG. 2;

FIG. 4 is a view of a collateral opening of the eversible branch stent-graft seen as viewed along line IV of FIG. 2;

FIG. 5 is an enlarged cross-sectional view, partially cutaway, of the eversible branch stent-graft of FIG. 3 during eversion of a branch stent-graft; and

FIG. 6 is a side view of the eversible branch stent-graft deployed in the main vessel in accordance with one embodiment.

Common reference numerals are used throughout the drawings and detailed description to indicate like elements.

DETAILED DESCRIPTION

Referring to FIG. 2, a method includes deploying an eversible branch stent-graft 100 into a main vessel 202 such that a collateral opening 114 in a main stent-graft 104 of eversible branch stent-graft 100 is aligned with an ostium 216 of a branch vessel 210 emanating from main vessel 202. A branch anchor suture 220 is removed to release a protruding end 106P of a branch stent-graft 106 from a proximal end 104P of main stent-graft 104.

Referring now to FIGS. 2 and 3 together, a branch stent ring suture 222 threaded through outer exposed crowns 130 of an outer stent ring 122 of branch stent-graft 106 is grasped and pulled through collateral opening 114 to evert branch stent-graft 106 into branch vessel 210 as illustrated in FIG. 6.

Referring again to FIG. 2, protruding end 106P of branch stent-graft 106 is initially located at proximal end 104P of main stent-graft 104. Further, collateral opening 114 is aligned with ostium 216 of branch vessel 210. Accordingly, a portion of the blood flow through main vessel 202 enters branch stent-graft 106 at protruding end 106P, travels through a branch lumen 118 of branch stent-graft 106, exits through collateral opening 114 and passes into branch vessel 210 as indicated by the arrows 218.

In this manner, branch vessel 210 is perfused through branch stent-graft 106 during the entire procedure of deploying everted branch stent-graft 100. Accordingly, perfusion to the brain via the carotids is not interrupted for any significant interval of time reducing the complexity and risk of the procedure. Further, deployment of branch stent-graft 106 into branch vessel 210 is simple and direct.

More particularly, FIG. 1 is a side view of an eversible branch stent-graft 100, e.g., a thoracic aortic stent-graft, in a deployed configuration in accordance with one embodiment. Referring now to FIG. 1, eversible branch stent-graft 100 includes a plurality of primary stent rings 102 and a proximal exposed stent ring 103. Illustratively, primary stent rings 102 and proximal exposed stent ring 103 are self-expanding stent rings, e.g., formed of Nitinol.

Eversible branch stent-graft 100 includes a main stent-graft 104 and a branch stent-graft 106 coupled to one another. Main stent-graft 104, e.g., a Valiant® Stent Graft available from Medtronic, Inc., includes a graft material 108, e.g., graft cloth, and stent rings 102, 103 coupled, e.g., sewn, to graft material 108.

Main stent-graft 104 includes a proximal main opening 110 at a proximal end 104P of main stent-graft 104 and a distal main opening 112 at a distal end 104D of main stent-graft 104. Proximal exposed stent ring 103 is attached to graft material 108 at proximal end 104P of main stent-graft 104.

Further, main stent-graft 104 includes a longitudinal axis L1. A main lumen 113 is defined by main stent-graft 104 and extends generally parallel to longitudinal axis L1 and between proximal main opening 110 and distal main opening 112 of main stent-graft 104.

Main stent-graft 104 is curved, e.g., to accommodate the aortic arch. More particularly, main stent-graft 104 includes an inner radius of curvature IR and an outer radius of curvature OR. Graft material 108 of main stent-graft 104 is thus sometimes said to define a curved cylindrical surface. However, in another example, a main stent-graft similar to main stent-graft 104 is formed with a straight cylindrical graft material.

As used herein, the proximal end of a prosthesis such as a stent-graft is the end closest to the heart via the path of blood flow whereas the distal end is the end furthest away from the heart during deployment. In contrast and of note, the distal end of the catheter is usually identified to the end that is farthest from the operator (handle) while the proximal end of the catheter is the end nearest the operator (handle).

For purposes of clarity of discussion, as used herein, the distal end of the catheter is the end that is farthest from the operator (the end furthest from the handle) while the distal end of the prosthesis is the end nearest the operator (the end nearest the handle), i.e., the distal end of the catheter and the proximal end of the stent-graft are the ends furthest from the handle while the proximal end of the catheter and the distal end of the stent-graft are the ends nearest the handle. However, those of skill in the art will understand that depending upon the access location, the stent-graft and delivery system description may be consistent or opposite in actual usage.

Formed within main stent-graft 104 is a collateral opening 114. Collateral opening 114 is an opening in graft material 108. Generally, the area defined by collateral opening 114 lies upon the curved cylindrical surface defined by graft material 108 at or near the outer radius of curvature OR. Collateral opening 114 is described in greater detail below with reference to FIG. 4.

Branch stent-graft 106 is coupled, e.g. sewn, to main stent-graft 104 at a location between proximal main opening 110 and distal main opening 112 of main stent-graft 104. More particularly, a graft end 106G (sometimes called a proximal end in the deployed configuration of FIG. 1) of branch stent-graft 106 is sewn to graft material 108 of main stent-graft 104 around collateral opening 114, which forms an inner opening (sometimes called a proximal opening in the deployed configuration of FIG. 1) for branch stent-graft 106. In the example illustrated in FIG. 1, branch stent-graft 106 is attached between the second and third most proximal stent rings 102.

Branch stent-graft 106 further includes an outer opening 116 at a protruding end 106P (sometimes called a distal end in the deployed configuration of FIG. 1) of branch stent-graft 106. Further, branch stent-graft 106 includes a longitudinal axis L2 substantially perpendicular to longitudinal axis L1 of main stent-graft 104. A branch lumen 118 is defined by branch stent-graft 106 and extends generally parallel to longitudinal axis L2 and between collateral opening 114 and outer opening 116 of branch stent-graft 106.

Branch stent-graft 106 includes a tubular graft member 120 and an outer stent ring 122 (sometimes called a distal stent ring in the deployed configuration of FIG. 1). In one example, tubular graft member 120 is a graft material braid 124 with several strands of wire 126, e.g., Nitinol wire, incorporated into the braid. An example of tubular graft member 120 includes braided polyester along with a Nitinol wire for stability, available from Secant Medical. The tubular graft member 120 may also comprise a woven cloth tube. The tube may be woven in a tubular shape, or the tube may be created from a flat rectangle of cloth with opposite edges joined by any appropriate means.

Outer stent ring 122 is coupled, e.g., sewn, to tubular graft member 120 at protruding end 106P of branch stent-graft 106. An example of outer stent ring 122 includes a bare nitinol spring as is known in the art. As discussed in greater detail below, outer stent ring 122 is a sinusoidal pattern having inner attached crowns 128 and outer exposed crowns 130. Crowns 128, 130 are sometimes called the minima and maxima, or peaks and valleys of outer stent ring 122.

Inner attached crowns 128 are coupled, e.g., sewn, to tubular graft member 120 at protruding end 106P of branch stent-graft 106 thus coupling outer stent ring 122 to tubular graft member 120. Outer exposed crowns 130 are exposed, i.e., project freely from tubular graft member 120 facilitating capture and manipulation with a branch stent ring suture as discussed further below. The outer stent ring 122 also establishes fixation and seal when finally positioned.

FIG. 2 is a schematic cross-sectional view of eversible branch stent-graft 100 of FIG. 1 being deployed in a main vessel 202 in accordance with one example. In FIG. 2, primary stent rings 102 and proximal exposed stent ring 103 are not illustrated for clarity of presentation. Further, main stent-graft 104 is illustrated as being transparent to illustrate features therein, however, it is to be understood that main stent-graft 104 may be opaque in actual usage.

Referring now to FIG. 2, eversible branch stent-graft 100 is deployed into a main vessel 202 using any one of a number of well known techniques, the particular delivery/deployment technique used is not essential.

Further, as illustrated in FIG. 2, eversible branch stent-graft 100 is in a pre-deployment configuration, sometimes called a delivery configuration. In the pre-deployment configuration, branch stent-graft 106 is everted (turned inside out) inside of main lumen 113 of main stent-graft 104. More particularly, graft end 106G of branch stent-graft 106 remains attached to graft material 108 of main stent-graft 104 as discussed above. Protruding end 106P is located within proximal main opening 110 and at proximal end 104P of main stent-graft 104.

Main vessel 202, e.g., the aorta, includes an aneurysm 204, e.g., a thoracic aortic aneurysm (TAA). Generally, main stent-graft 104 seals against main vessel 202 above and below, e.g., proximally and distally to, aneurysm 204. Accordingly, fluid flows through main lumen 113 of main stent-graft 104 thus bypassing and excluding aneurysm 204.

Branching off main vessel 202 are three branch vessels 206, 208, 210, e.g., the subclavian, the common carotid, and the brachiocephalic trunk. In the example illustrated in FIG. 2, main stent-graft 104 is deployed proximally to branch vessels 206, 208, 210 covering (over) the ostia (plural of ostium) 212, 214, 216 of branch vessels 206, 208, 210, respectively.

However, branch vessels 206, 208, 210 are perfused through branch stent-graft 106. More particularly, prior to deployment of eversible branch stent-graft 100, a well known preliminary procedure to create a right-left carotid bypass and a left-carotid-subclavian bypass is performed. This preliminary procedure insures that perfusion to branch vessel 210 perfuses branch vessels 206, 208. Stated another way, this preliminary procedure provides that a portion of the blood flow into branch vessel 210 is redirected to branch vessels 206, 208 as those of skill in the art will understand.

As set forth above, protruding end 106P and thus outer opening 116 is located within proximal main opening 110. Further, eversible branch stent-graft 100 is deployed such that collateral opening 114 is aligned with ostium 216 of branch vessel 210. Accordingly, a portion of the blood flow through main vessel 202 enters outer opening 116 at protruding end 106P of branch stent-graft 106, travels through branch lumen 118, exits through collateral opening 114 and into branch vessel 210 as indicated by the arrows 218.

In this manner, branch vessel 210 and thus all of branch vessels 206, 208, 210 are perfused through branch stent-graft 106 during the entire procedure of deploying everted branch stent-graft 100. Accordingly, perfusion to the brain via the carotids is not interrupted for any significant interval of time reducing the complexity and risk of the procedure.

FIG. 3 is an enlarged cross-sectional view, partially cutaway, of a region III of eversible branch stent-graft 100 of FIG. 2. Referring now to FIGS. 2 and 3 together, everted branch stent-graft 100 includes a branch anchor suture 220 and a branch stent ring suture 222.

Branch anchor suture 220 is a single continuous suture that sutures (attaches) protruding end 106P of branch stent-graft 106 to proximal end 104P of main stent-graft 104.

Branch anchor suture 220 extends through graft material 108 of main stent-graft 104 and through tubular graft member 120 of branch stent-graft 106, i.e., is stitched to graft material 108 and tubular graft member 120. In one example, branch anchor suture 220 is a single stitch between graft material 108 and tubular graft member 120 facilitating easy removal of branch anchor suture 220.

As branch anchor suture 220 is a single continuous suture, branch anchor suture 220 has two ends 224, 226. Branch anchor suture 220 extends proximally (towards the handle) from protruding end 106P of branch stent-graft 106 and proximal end 104P of main stent-graft 104, though main lumen 113, through the lumen of the graft cover (not shown) and exits the patient, e.g., through a luer fitting. More particularly, at least one of ends 224, 226 exits the patient.

To remove branch anchor suture 220 thus releasing protruding end 106P of branch stent-graft 106 from proximal end 104P of main stent-graft 104, end 224 (or end 226) is pulled proximally as indicated by arrow 228 causing end 226 (or end 224) to move distally as indicated by arrow 230. End 226 (or end 224) thus slips out of both graft material 108 of main stent-graft 104 and tubular graft member 120 of branch stent-graft 106 releasing protruding end 106P of branch stent-graft 106 from proximal end 104P of main stent-graft 104. Branch anchor suture 220 is pulled until end 226 (or end 224) is removed from the patient thus completely removing branch anchor suture 220.

In light of this disclosure, those of skill in the art will understand that any one of a number of delivery catheters can be designed to facilitate removal of branch anchor suture 220 and the particular catheter used is not essential.

In the view of FIGS. 2 and 3, branch stent-graft 106 is everted (inside out), whereas in the view of FIG. 1, branch stent-graft 106 in uneverted (right side out). To further illustrate, referring to FIGS. 1, 2 and 3 together, branch stent-graft 106 includes a first surface 132 and a second surface 134, e.g., cylindrical surfaces opposite one another. In the deployed configuration as illustrated in FIG. 1, first surface 132 is the outer surface of branch stent-graft 106. In contrast, in the delivery configuration as illustrated in FIGS. 2-3, second surface 134 is the outer surface of branch stent-graft 106.

Further, as illustrated in FIGS. 1, 2, and 3, the orientation and configuration of outer stent ring 122 is maintained uneverted. In the delivery configuration the tubular graft member 120 of the branch stent graft 106 is everted around the stent ring 122, upon deployment of the main stent graft 104, the stent ring 122 keeps the tubular graft member 120 of the branch stent graft 106 open to perfuse the branch vessel 210 during the time of branch manipulation and deployment. During the process of branch stent graft 106 deployment the stent ring 122 is pulled through the everted tubular graft member 120 to turn it right side out as it follows the stent ring 122 out the collateral opening 114. Paying particular attention to FIG. 3, tubular graft member 120 is folded over at protruding end 106P in the delivery configuration. More particularly, tubular graft member 120 is folded over at a fold 301 such that a first portion 302 of tubular graft member 120 extends back inside of the remaining second portion 304 of tubular graft member 120. Portion 302 is attached, e.g., sewn, to inner attached crowns 128 of outer stent ring 122.

FIG. 4 is a view of collateral opening 114 of eversible branch stent-graft 100 taken along the line IV of FIG. 2. As illustrated in FIG. 4, collateral opening 114 is ellipsoidal having a greater first width W1 parallel to longitudinal axis L1 than a second width W2 perpendicular to longitudinal axis L1. The ellipsoidal shape of collateral opening 114 has been found to produce a lumen of the largest cross sectional area branch stent-graft 106 to make the turning of the tubular graft member 120 right side out easier than when a circular opening known in the art is used.

Referring now to FIGS. 2, 3, and 4 together, branch stent ring suture 222 is a closed loop of suture, i.e., has no free ends. Branch stent ring suture 222 has been threaded through outer exposed crowns 130 of outer stent ring 122. Branch stent ring suture 222 is packed in the everted tubular graft member 120 and extends from outer stent ring 122, through branch stent-graft 106 to have a grasping end loop 402 adjacent collateral opening 114. In one embodiment, to facilitate the eversion, grasping end loop 402 of branch stent ring suture 222 is performed, sometimes called snared, with a tool advanced through branch vessel 210, e.g., via an introducer in the carotid or brachial artery. The tool can take any one of a number of shapes to snare grasping end loop 402 of branch stent ring suture 222, e.g., a hook shaped tool, a helical tool, or other shaped tool. The particular tool used is not essential to this example. In one example, end loop 402 of branch stent ring suture 222 is located within branch stent-graft 106 and thus the tool must be advanced through collateral opening 114 to grasp end loop 402 and pull it out of the branch stent graft 106. The length of the branch stent ring suture 222 loop once extended is long enough to extend through a patient's anatomy to and out the carotid or brachial artery access opening. In one configuration once the packed loop is extended outside the patient's body thereby putting the outer stent ring 122 of the branch stent graft 106 under the direct control of the implanting physician. In another configuration the packed loop is long enough to be grabbed securely by the snare catheter, which after branch graft deployment can hold the loop securely as it is cut by that or another catheter to release tension on the loop and safely extract the remnant of the loop from the patient's body.

Once the end loop 402 of branch stent ring suture 222 is under control of the physician, the protruding end 106P of branch stent-graft 106 can be released from main stent-graft 104 by removal of branch anchor suture 220 as discussed above, As the branch anchor suture 220 is released, branch stent-graft 106 begins to self-evert (turn inside out) due to the flow of blood through branch stent-graft 106 in one example. The amount of self-eversion (turning inside out) depends upon the particular application and can vary from complete eversion to no eversion. Simultaneously with the self eversion, the physician can pull on the branch stent ring suture 222 to guide the branch stent ring 130 to the collateral opening 114.

Once the branch anchor suture 220 loop is free of the branch stent graft 106, the branch stent ring suture 222 is then further pulled, i.e., through tubular graft member 120 and out of collateral opening 114, causing branch stent-graft 106 to evert into branch vessel 210 as explained in greater detail below with reference to FIG. 5.

FIG. 5 is an enlarged schematic cross-sectional view, partially cutaway, of eversible branch stent-graft 100 of FIG. 3 during eversion of branch stent-graft 106. As illustrated in FIG. 5, retraction of branch stent ring suture 222 in the direction of arrow 502 causes outer exposed crowns 130 to be pulled together in apposition due to the application of tension. This causes outer stent ring 122 to assume a conical shape, having a leading apex 504. This conical shape, sometimes called a conical leading profile, enhances passing of outer stent ring 122 though tubular graft member 120, through collateral opening 114 and into branch vessel 210 as illustrated in FIG. 6.

FIG. 6 is a side view of eversible branch stent-graft 100 deployed in main vessel 202 in accordance with one embodiment. Referring now to FIGS. 5 and 6 together, once branch stent ring suture 222 is pulled to completely extend branch stent-graft 106 within branch vessel 210, branch stent-graft 106 is completely everted and has an absence of folds, i.e., no portion of branch stent-graft 106 extends back into itself. Branch stent ring suture 222 is cut and removed from outer stent ring 122 through branch vessel 210. Accordingly, deployment of branch stent-graft 106 into branch vessel 210 is simple and direct.

Although perfusion of and deployment into branch vessel 210 is set forth above, in other examples, branch stent-graft 106 is deployed into other branch vessels, e.g., into branch vessel 206 or branch vessel 208.

In one example, completion of the procedure is accomplished by deploying a Palmaz stent within branch stent-graft 106 well distal to the junction between main stent-graft 104 and branch stent-graft 106. This ensures that this junction is mobile and deformable to accommodate the well documented, large displacement motions of the ascending aorta during the cardiac cycle.

This disclosure provides exemplary embodiments. The scope is not limited by these exemplary embodiments. Numerous variations, whether explicitly provided for by the specification or implied by the specification or not, such as variations in structure, dimension, type of material and manufacturing process may be implemented by one of skill in the art in view of this disclosure. 

What is claimed is:
 1. An eversible branch stent-graft comprising: a main stent-graft defining a main lumen, wherein said main lumen comprises a first opening at a proximal end and a second opening at a distal end with said main lumen extending from said first opening to said second opening; and an everted branch stent-graft inside of said main lumen, said everted branch stent-graft comprising: a graft end attached to graft material of said main stent-graft around a collateral opening in said main stent-graft; a protruding end; a tubular graft member located between said graft end and said protruding end; and an outer stent ring attached to said tubular graft member, said outer stent ring comprising: inner attached crowns attached to said tubular graft member; and outer exposed crowns; a branch anchor suture releasably attaching said protruding end of said everted branch stent-graft to said proximal end of said main stent-graft, wherein said branch anchor suture is a single continuous suture comprising a first end and a second end, wherein said first end and said second end extend out of said second opening at said distal end of said main stent-graft, and further wherein pulling said first end causes said branch anchor suture to release said protruding end of said everted branch stent-graft from said main stent-graft; and a branch stent ring suture threaded through said outer exposed crowns, said branch anchor suture and said branch stent ring suture being separate sutures.
 2. The eversible branch stent-graft of claim 1 wherein said eversible branch stent-graft is in a delivery configuration.
 3. The eversible branch stent-graft of claim 1 wherein said branch anchor suture extends through said graft material of said main stent-graft and through said tubular graft member of said everted branch stent-graft.
 4. The eversible branch stent-graft of claim 1 wherein said graft material of said main stent-graft is stitched to said tubular graft member of said everted branch stent-graft by said branch anchor suture.
 5. The eversible branch stent-graft of claim 1 wherein said tubular graft member comprises: a graft material braid; and several strands of wire incorporated into said graft material braid.
 6. The eversible branch stent-graft of claim 1 wherein said branch stent ring suture is a closed loop of suture.
 7. The eversible branch stent-graft of claim 1 wherein said branch stent ring suture comprises a grasping end loop, said branch stent ring suture extending from said outer stent ring, through said branch stent-graft such that said grasping end loop is accessible through said collateral opening.
 8. The eversible branch stent-graft of claim 1 wherein said tubular graft member is folded over at said protruding end of said branch stent-graft.
 9. The eversible branch stent-graft of claim 8 wherein a first portion of said tubular graft member extends back inside of a second portion of said tubular graft member.
 10. The eversible branch stent-graft of claim 9 wherein said first portion is attached to said outer stent ring.
 11. The eversible branch stent-graft of claim 1 wherein said collateral opening is ellipsoidal.
 12. The eversible branch stent-graft of claim 11 wherein said collateral opening has a first width parallel to a longitudinal axis of said main stent-graft and a second width perpendicular to said longitudinal axis, said first width being greater than said second width.
 13. An eversible branch stent-graft comprising: a main stent-graft defining a main lumen, wherein said main lumen comprises a first opening at a proximal end and a second opening at a distal end with said main lumen extending from said first opening to said second opening; an everted branch stent-graft comprising: a graft end attached to a graft material of said main stent-graft around an ellipsoidal collateral opening in said main stent-graft; a protruding end; a tubular graft member located between said graft end and said protruding end, said tubular graft member comprising: a graft material braid; and several strands of wire incorporated into said graft material braid; and an outer stent ring attached to said tubular graft member at said protruding end, said outer stent ring comprising: inner attached crowns attached to said tubular graft member; and outer exposed crowns; a branch anchor suture releasably attaching said protruding end of said everted branch stent-graft to said main stent-graft, wherein said branch anchor suture is a single continuous suture comprising a first end and a second end, wherein said first end and said second end extend out of said second opening at said distal end of said main stent-graft, and further wherein pulling said first end causes said branch anchor suture to release said protruding end of said everted branch stent-graft from said said main stent-graft; and a branch stent ring suture threaded through said outer exposed crowns, said branch anchor suture and said branch stent ring suture being separate sutures. 